Indicator for renewable fuses



M. J. WEST y v INDICATOR'FO R RENEWABLE FUSES. APPLICATION FILEE) JULY 1I. 1.921.

1,421,051 Patented June 27, 1922.

UNITED STATES PATENT OFFICE.

MERLE J. WEST, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO WILLIAM D. KYLE, OF

I MILWAUKEE, WISCONSIN.

INDICATOR FOR RENEWABLE FUSES.

Specification of Letters Patent.

Patented June 27, 1922.

Original application filed May 20, 1919, Serial No. 298,478. Divided and this application filed July 11,

To all whom it may concern:

Be it known that I, MERLE J. WVEs'r, a citizen of the United States, and resident of Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented certain new and useful Improvements in Indicators for Renewable Fuses; and I do hereby declare that the following is a full, clear, and exact description thereof.

My invention relates to cut-outs for electric circuits, and particularly to indicators for cartridge fuses of the renewable type.

The present application is a division of my co-pending application Serial No. 2984178, filed llI-ay so, 1919.

The principal object of this invention is to provide a fuse of this type with an indicating device which will show when a fuse has blown without disassembling the de vice.

With this general object in view, it Will be seen that the invention resides in the novel features of construction, combination and arrangement of parts which will be hereinafter more particularly described and claimed and shown in the drawing in which:

Figure 1 represents an elevational view of a renewable cartridge fuse, parts being broken away and in vertical section to more clearly illustrate the interior construction.

Figure 2 is a detail sectional view of one end of the fuse, and

Figure 3 is a transverse sectional view taken substantially on the plane of the line of Figure 1.

In the embodiment illustrated, the invention is shown associated with a cartrid e fuse of the knife blade type, but it is to be understood that the same may be used in connection with the ordinary ferrule type, and further that various other minor changes may be made in the form and proportion and in the connection of the several parts, without departing from the principles of the invention. In all of its several forms the fuse will consist of an inner or housing casing having an opening covered by a hinged closure whereby the fusible link may be inserted thereinto, and an outer or protective shell telescopically engageable over the inner casing.

Referring to the drawing and considering the parts of the invention in detail, it will be seen that the fuse includes a cylindrical Serial No. 483,840.

open ended tube of fibre or other insulating and non-inflammable material which forms the major portion of a casing 1, said tube having an elongated opening formed in its wall intermediate its ends to permit access into the interior thereof after the open ends havebeen closed by ferrules 3 and 4 respectively. The opening 2 has its opposite ends rounded as at 2 and in width is substantially one-half the circumference of the tube. One longitudinal edge portion of the openlng 2 has a cover 5 hinged thereto as at 6, and the other edge portion carries one or more spring fingers 7 for engagement in recesses 8 in the cover for holding the same in locked position. This closure 5 for the opening 2 is substantially of the same configuration as the latter and when in closed position its edge is in abutting relation with the edge of said opening. This provides a very close fit between the opening and its cover and the latter has its outer surface flush with the corresponding surface of the easing 1. I

The ferrules 3 and 4 are secured to the ends of the casing 1 by crimping as at 9, and when the fuse is of the knife blade type, they carry the contact blades 10, the latter being preferably secured to the ferrules 3 and 4 in a manner indicated in Figures 1 and 2. That is to say the ferrule 3 for instance has a slot formed in itsorown to receive the'blade 10 which has a shoulder 11 for engagement with the inner side of the former, the outer portion of the blade being swaged against the crown of the ferrule at a plurality of points as at 12. A reinforcing pin 13 extends through the ferrule, the adjacent portion of the casing 1 and the blade as shown.

The inner end of each blade 10 is designed to form a fuse link attaching terminal 14 to which a fusible link 15 is connected. In their preferred construction, these attaching terminals are bifurcated as at 16 and provided with threaded screw holes to receive fastening screws 17. The'ends of the fusible link 15 have openings to align with the openings in the terminals when they are disposed between the furcations; the fastening screws 17 obviously secure the link in place.

All possibility of danger through the leakage of flame between the edges of the opening 2 and its cover 5 is obviated by the addition of an outer protective shell 18 which is of a size slightly greater than the inner casing 1 and is adapted to slide thereon. This protective shell is also formed from an open ended insulating and non-inflammable tube, one end of which is closed by a ferrule cap 19 crimped thereon as at 20, the crown of said ferrule cap having a slot to receive the adjacent contact blade 10. The opposite end of this tube has a reinforcing band 21 adapted to slide beneath a spring retaining collar 22 that is carried by the ferrule 3 and is preferably formed integrally therewith.

In assembling the protective shell on the inner casing 1, the open end of the former is slid over the ferrule 4: and the same moved longitudinally until said reinforcing band engages the retaining collar 22 as above mentioned. .Vhen this engagement takes place the crown of the ferrule cap 19 will have come into abutting relation with the crown of the ferrule 4t. Thus it will be seen that the outer protective shell 18 extends substantially throughout the length of the inner casing and completely covers the opening 2.

Ordinarily when a fuse link blows, considerable arcing occurs this even extending to the terminal attaching members, as the parts 11, and as a result they are mutilated and refilling is rendered dillicult. To overcome this ditiiculty I have disposed at carbon block 23 transversely of the inner casing 1 and substantially midway of the ends thereof, this block being of su'l'licient size to interrupt the air gap between the attaching terminals llto thereby prevent the flow of electricity between these parts. The block 23 is held in position by a spring clip 21 that has its ends 25 disposed through openings in the wall of the casing 1 and then bent laterally as particularly shown in Figure 3. The intermediate portion of the clip rests in a channel 26 formed in the block.

As hereinbefore mentioned the present invention also includes means for indicating the condition of the fusible link 15, that is to say whether or not the same is in operating condition or has been blown. In providing such an arrangement the block 23 is provided with a central hole for the reception of a cylindrical fibre plunger 27, the inner end of which. has a head 28 extended beyond the adjacent portion of the block for engagement with the fusible link 15. The opposite or outer end of the plunger is normally extended beyond the adjacent sur face of the block and through a hole 29 in the wall of the casing 1. A second hole 30 in the protective shell 18 is adapted to align with the hole 29 and disposed therein is the intermediate portion of an indicator button 31. Said button 31 is carried by and rigid with the intermediate portion of a spring plate 32, the opposite ends of which are secured to the wall of the shell 18.

When the fusible link 15 is in operative condition, it bears against the head 28 of the plunger 27 and causes the outer end of the latter to force the button 31 outwardly of the shell 18 indicated in Figures 1 and 3. As soon, however, as the link is blown, the tension of the spring plate 32 will be exerted to force the button inwardly so that the latter will be only slightly exposed, thus indicating to an observer that the fuse needs refilling.

Said observer may readily renew the fuse after taking the same from the switchboard or cut-out block, by slipping the protective shell 18 from oil the casing 1, thereby exposing the closure 5, after which said closure may be opened by releasing the spring finger 7 to permit access to the interior of the fuse. The portions of the blown fusible link are removed by taking out the screws 17, after which a new fusible link is inserted. The operations of assembling the several parts of the fuse are then carried out, said operations merely being the reverse of disassembling.

I claim:

1. A. fuse comprising a casing having an opening in its wall, terminal contact members closing the opposite ends of said casing, a spring plate having its o niosite ends secured to said casing, its intermediate portion being disposed across said opening, an indicator butt-mi carried by said intermedi ate portion of said plate and i'novable in said opening, a fusible link connecting said contact members, and means engaged with the button and the link when in operative condition.

2. A. fuse comprising a casing having an opening in its wall. terminal Contact members closing the opposite ends of said casing, a protective shell disposed around said casing and having an opening aligned with the first mentioned opening, an indicator button movable in the opening of the shell, a fusible link connecting said contact members, and a plunger in said casing and movable through said opening therein, the opposite ends of said plunger being normally engaged with the link and button respectively.

In testimony that claim the foregoing I have hereunto my hand at lililwankce in the county of hflilwaukce and State of lVisconsin.

MERLE J. WEST. 

